There has been studied a service that provides data including a variety of large-capacity contents using a high-definition image (including a moving image or a still image) or a sound to an end user through a wireless communication. In order to transmit large-volume data of several G (giga) bits at a high speed, there has been studied a wireless communication system that performs high-speed transmission of several Gbps with the use of a millimeter waveband including a 60 GHz band.
In the millimeter wave wireless communication system, a standardization work is conducted in an IEEE by, for example, IEEE 802.15.3c as a wireless PAN (personal area network), and by, for example, IEEE 802.11ad as a wireless LAN (local area network).
For example, in a single carrier transmission system using the millimeter waveband which has been studied in the IEEE802.11ad, a signal that has been subjected to PSK or QAM modulation is transmitted at 1.76 G symbols/sec. Data transmission at a super high speed where a time of one packet is short, that is, several μsec to several tens μsec, and a short inter-frame spacing is also short, that is, 3 μsec, is conducted. For that reason, an allowable latency for modulation and demodulation processing is short, and high speed arithmetic processing is required.
In a semiconductor circuit of an LSI that performs the high speed arithmetic processing, a size of transistors formed interiorly is increasingly miniaturized with an improvement of an operating frequency. However, there arises such a problem that the miniaturization causes an increase in leakage current.
A main cause of the leakage current is a quantum tunneling effect, which is generated by allowing electrons to pass through an insulator disposed between electric conductors located at a short distance. When a process rule of a digital semiconductor circuit requiring the high speed arithmetic operation becomes 100 nm or lower, more than half of a power consumed by the semiconductor circuit is consumed as the leakage current.
In the signal processing semiconductor circuit used in the millimeter wave wireless communication device that performs high speed transmission, for the purpose of reducing a power consumption, a power gating control that turns off a power supply of an unused circuit is an issue.
As a technique for reducing the power consumption in the wireless communication device, Patent Literatures 1 and 2 have been known. Patent Literature 1 discloses a technique in which when it is determined that an own device is not a destination at the time of receiving a header of an upper layer frame, a mode is shifted to a power saving mode on the basis of a length of the upper layer frame extracted from a header of a physical layer frame. Also, Patent Literature 2 discloses a technique in which a power supply is separate for each of arithmetic blocks in a semiconductor integrated circuit, and when input data effective in a buffer section of each arithmetic block could be prepared, a switch section that supplies a power to the arithmetic block is controlled, to thereby reduce a leakage current and realize a reduction in the power consumption.